A massive fire and a series of explosions at a private chemical container depot in southeastern Bangladesh killed at least 49 people, including nine firefighters, and injured more than 450 others, officials said on Sunday, as authorities were still struggling to extinguish the blaze.

According to doctors, the toll could rise further as many of the injured people were being treated with severe burns. The firefighters backed by army troops were yet to enter deep down the blast site to douse the fire nearly 23 hours after the fire broke out on Saturday.

"The fire was caused by chemicals including hydrogen peroxide, making the situation difficult,” fire service chief Brigadier General Mohammad Mainuddin told reporters at the scene where the firefighters were trying to extinguish the blaze amid intermittent explosions since Saturday evening.

The official expected the firefighters to put out the blaze and halt the explosions by tonight. The disaster prompted authorities to call out army sappers to prevent the spread of chemicals in nearby canals and the coastlines of the Bay of Bengal.

Fire service officials said nine of their colleagues were killed in explosions as they rushed to the scene immediately after the blaze was reported at the BM Container Depot in Sitakunda at the outskirts of the port city of Chattogram.

This was the first time in known Bangladesh history when so many firefighters were killed in the line of duty in a single such disaster. "So far 49 bodies arrived at the (Chattogram Medical College Hospital or CMCH) morgue,” police sub-inspector at the facility Mohammad Alauddin told reporters.

Doctors at the state-run CMCH, which accommodated most of the wounded people, said the fate of over a dozen of the burn-injured patients was uncertain due to their critical wounds.

Dozens more including firefighters are being treated at the Chattogram Combined Military Hospital (CMH) while Prime Minister Sheikh Hasina ordered military helicopters to bring the critically wounded patients to Dhaka for better treatment.

Hospitals in the area are overwhelmed, with crowds of people waiting in hallways for treatment.?Pictures of the aftermath showed the twisted remains of metal shipping containers and the collapsed roof of a warehouse.

Chattogram Divisional Commissioner (DC) Ashraf Uddin said that families of the deceased would be given USD 560 (Taka 50,000) by the DC office, and USD 224 (Taka 20,000) would be given to the families of the injured, the Daily Star newspaper reported.

Bangladesh’s parliament, which met on its maiden budget session on Sunday, adopted a condolence motion over the tragedy. Officials and witnesses speculated that the firefighters were initially unaware that the depot stored chemicals to cause blasts while video footage which went viral showed a teenage boy doing Facebook live and moments later virtually vanishing alongside the firemen.

"The deafening explosions turned the sky a blazing orange throughout the night,” a resident in the neighbourhood told a TV channel adding that the explosions threw several people metres away from where they were standing.

The residents said the explosions rocked the neighbourhood within a nearly four-kilometre radius around the inland container depot which has been operating since May 2011. A pungent odour in the air forced rescuers to cover their noses in masks while they also complained of itching eyes apparently due to chemicals.

Officials said the depot -- a site with 21 acres of land -- stored around 4,000 containers, many filled with garments destined for Western retailers.

In a statement, Mujibur Rahman, director of the BM Container Depot, said it was not clear what caused the fire. "But I think the fire started from the container". "Arrangements are being made to ensure that the injured get the best treatment. We will bear the entire cost of the treatment. Those who were injured in the accident will be given the maximum compensation," Rahman was quoted as saying by The Daily Star newspaper.

"In addition, we will take responsibility for all the families of all the victims," he added. Bangladesh has a history of industrial disasters. Past industrial tragedies have often been attributed to safety lapses.

Last year, a fire engulfed a food and drink factory in Bangladesh, killing at least 52 people. In February 2019, a blaze ripped through a 400-year-old area cramped with apartments, shops and warehouses in the oldest part of Dhaka and killed at least 67 people.

In 2012, about 117 workers died when they were trapped behind locked exits in a garment factory in Dhaka. The country’s worst industrial disaster occurred the following year, when the Rana Plaza garment factory outside Dhaka collapsed, killing more than 1,100 people.

Another fire in Old Dhaka in a house illegally storing chemicals killed at least 123 people in 2010.?